CBSE Class 9 Answered

HIV, the virus that causes AIDS, damages and destroys different cells of the immune system. When these cells are destroyed, the body cannot recognize infections. Even if infections are recognized, the body may be unable to defend itself against them. When HIV damages the immune system a person may get opportunistic infections. These are diseases, infections and cancers that use the opportunity of a weak immune system to  make their way into the body. Common infections can be life-threatening to people with HIV or AIDS who have very weak immune systems.

Treating HIV infection is hard, in part because the virus can change its proteins and becomedrug resistant . This means that the virus learns to grow even when the anti-HIV drugs are in your body.